{
  "flow":[
    {
      "tasks":[
        { "id":"1", "uid":"bryan" },
        { "id":"2", "uid":"eric" }
      ]
    },
    {
      "tasks":[
        { "id":"1", "uid":"bryan" },
        { "id":"2", "uid":"eric" }
      ]
    },
    {
      "tasks":[
        { "id":"1", "uid":"bryan" },
        { "id":"2", "uid":"eric" }
      ]
    },
    {
      "tasks":[
        { "id":"1", "uid":"bryan" },
        { "id":"2", "uid":"eric" },
        { "id":"3", "uid":"eric" },
        { "id":"4", "uid":"bryan" }
      ]
    }
  ]
}

{
  "flow":[
    {
      "tasks":[
        { "id":"2", "uid":"eric" },
        { "id":"1", "uid":"bryan" }
      ]
    },
    {
      "tasks":[
        { "id":"2", "uid":"eric" },
        { "id":"1", "uid":"bryan" }
      ]
    },
    {
      "tasks":[
        { "id":"2", "uid":"eric" },
        { "id":"1", "uid":"bryan" }
      ]
    },
    {
      "tasks":[
        { "id":"2", "uid":"eric" },
        { "id":"3", "uid":"eric" },
        { "id":"1", "uid":"bryan" },
        { "id":"4", "uid":"bryan" }
      ]
    }
  ]
}

function reorder_flow($flow, $uid)
{
    foreach($flow as &$step)
    {
        //step is the array with tasks
        $tasks = $step['tasks'];
        $new_tasks = array();

        foreach($tasks as $key => $t)
        {
            if($t['uid'] == $uid)
            {
                $new_tasks = $new_tasks + $t;
                unset($tasks[$key]);
            }
        }
        $step['tasks'] = $new_tasks + $step['tasks'];
    }
    return $flow;
}